The Mekons are a great, rather obscure, Marxist post-punk/country band that's been around for about a quarter-century. The good news is that they live their politics and give away free music. Go to the link above and click on "music." Listen to "Memphis, Egypt," as good a song as has been recorded in the last 20 years.
Marxists giving away free music reminds me of the time I went into a Christian-owned market in Charlottesville, VA, when I was in grad school. The prices were incredibly low, so I asked the owner how she was able to do it. She said that, "it's easy if you don't believe in the idea of profit."